Shading effect in walls gains without windows

Question

Hello, 
 I would like to know why I cannot find any effect of shading on a wall gains that does not have windows. When I do the Cibse Gain calcs., the results are the same! (if the wall has windows, the results are different with or without shading). 
 Regards, 
 Jose

Shane Regan · Accepted Answer

Hi Jose, 
 
I can confirm that the same results are to be expected. Wall shading is not considered in Design Database, only window shading. 
 
Regards, 
Shane

Shane Regan · Answer

Hi Jose, 
 Are you referring to the tick-box as below? 
 
 If so then please note that you must define the external buildings in the Shadows function in Design Database - have you done so? Please see extract from the Hevacomp manual below (press F1 in Hevacomp to access this). 
 If you opt to include external shading, the calculation will check if each window is shaded by external obstructions at each hour of the day. Shaded windows will receive diffuse solar radiation only. Use the Shadows module to set up external buildings.

Shane Regan · Answer

Hi Jose, 
 
The reduction in heat gains you are seeing when there is a window present is that due to the direct component of solar radiation being blocked by the adjacent building. 
 
In the case of walls only there is no direct component, only diffuse, so the shading does not affect this. 
 
I hope this helps to clarify.